Summary of intervention protocols across the included studies, detailing the type of therapy, specific exercises, duration, frequency, and control conditions.
| Study | Intervention therapy | Details | Duration | Frequency | Control therapy |
|---|---|---|---|---|---|
| Villa et al. (2015) [11] | OE | Isometric and isotonic exercises, nasal breathing rehabilitation, labial seal and lip tone exercises, and tongue posture exercises | 2 months | Three times/day, 10–20 repetitions each time | Nasal washing |
| Diaferia et al. (2013) [18] | Myofunctional therapy + CPAP therapy | Soft palate, pharyngeal constrictor muscles, suprahyoid muscles, tip and root of the tongue, cheeks, and lips | 3 months | 20 min, 3 times/day | Head movements without any therapeutic function |
| Diaféria et al. (2017) [19] | Myofunctional therapy + CPAP therapy | 1) Soft palate exercises2) Tongue brushing3) Tongue pushing and sucking4) Tongue rotation5) Facial exercises | 3 months | 1) 3 min, 3 times/day2) 5 min, 3 times/day3) 20 min, 3 times/day4) 10 min on each side, 3 times/day | Head movements without any therapeutic function |
| Erturk et al. (2020) [20] | 2 groups:1) Passive myofunctional therapy with oral device2) Active myofunctional therapy | 1) IMT with a threshold IMT device2) OE included soft palate, tongue, and facial muscle exercises | 12 weeks | 7 days/week5 days/week | Control group not specified |
| Guimarães et al. (2009) [21] | OE | Exercises for the soft palate, tongue, and facial muscles | 3 months | Repeated exercises for a total of about 20 min per day | Deep breathing and nasal washing |
| Villa et al. (2017) [22] | OE | 1) Nasal breathing rehabilitation2) Labial seal and lip tone exercises3) Tongue posture exercises | 2 months | Three times a day, 10–20 repetitions each time | Nasal washing |
| Ieto et al. (2015) [23] | Nasal washing and OE | Exercises for the soft palate, tongue, and stomatognathic functions | 3 months | 8 min set of exercises (20 times), 3 times/day | Deep breathing and nasal washing |
| Kim et al. (2020) [24] | Myofunctional therapy | Tongue and lips exercises | 12 weeks | Perform 10 exercises with 10 repetitions each, and perform at least 10 sets every day | Control group that did not receive any treatment |
| Lin et al. (2020) [25] | Daily nasal washing + myofunctional therapy and general endurance training | Retropalatal, retroglossal, hypopharyngeal, facial, and TMJ exercises | 12 weeks | 24 sessions, daily nasal washing + upper airway muscle strengthening for 20 min, respiratory muscle strengthening for 15 min, and general endurance training for 45 min | Control group that did not receive any treatment |
CPAP: continuous positive airway pressure; IMT: inspiratory muscle training; OE: oropharyngeal exercises; TMJ: temporomandibular joint.